Auxiliary airfoil



July 18, 1944. E. D. SHANNON 2,353,855

AUXILIARY AIRFOIL FiledNov. 21, 1942 ZSheets-Sheetl FIGURE l FIGURE 2 v INVENTOR.

EL.L IS D. SHANNON AT'T I NEY .uly 18, 1944.

E. D. SHANNON 2,353,856

AUXILIARY AIRFOIL Filed Nov. 21, 1942 2 Sheets-Sheet 2 FIGURE: 4

INVENTOR. ELLIS D. SHANNON AT'TO Patented July 18, 1944 UNITED ;STATES PATENT OFFICE 2,353,856 auxmmltr AIRFOIL Ellis D. Shannon, Baltimore, Md.', assignor to The I Glenn L. Martin Company, Middle River, Md., a corporation of Maryland Application November 21, 1942, Serial No. 466,445

. 2 Claims. ((1244-87) ioent the intersection of two stabilizers when one stabilizer control surface has to be out to permitthe deflection of the other,

In empennage of the twin rudder and stabil izer type. it is necessary to cut the elevator to allow for deflection of the rudders.

. which result in vibration or oscillation of the rudder, that is carried through the control system and causes annoying vibration of the rudder pedals and yoke, and-may, of. course, ultimately cause damage to the empennage.

The structure of this invention can readily be adapted to most twin rudder and stabilizer empennage, and can be installed with very little modification of the existing structure.

Further and other objects will become apparent from the description of the accompanying drawings which form a part of this disclosure and in which like numerals refer to like parts.

In the drawings:

Figure 1 shows a twin rudder and stabilizer Figure 2 is a perspective of the underside ofthe stabilizer and elevator.

Figure} is a perspective view of the of the stabilizer and elevator. a

Figure 4 is a sectional view through the stabilizer and elevator. p

Figure 5 is a perspective view from the rear .of the fuselage of the top side of the stabilizer.

Figure 6 is a partial plan view showing the elevator cut to allow for rudder deflection.

Figure l of the drawings, shows a twin rudder empennage attached to the rear end of themselage I, The empennage comprises elevator stabilizers 2 so positioned on the fuselage that a dihedral angle is formed therebetween. Elevators I are attached to stabilizers 2, and are cut out as shown at l to afi'ord clearance for ruddertop side deflection. The rudders '5 are secured to sta-- bilizers '6 which aremounted substantially normal to the stabilizers 2.. Deicer boots I are shown on the leading edge of all stabilizers. The auxlliary airfoils 8 and ,9 are mounted secured to the rudder stabilizer by brackets l0 and spaced v This cut in the elevator causes irregular flow conditions greater than the lateral extent of the cut-out ortion of airfofl 3. The length of the auxiliary airfoil should be long enough to affect a smooth flow of air over the cut-out portion of airfoil 3; In other words, the eflective length of the auxlliary airfoil 8 should be substantially equal to the lateral extent of the cut-out portion.

The auxiliary airfoil .may readily be attached to existing installations as the bracket l0 can easily be secured to the rudder stabilizer and the support H can be secured in the elevator hinge bracket slot. The auxiliary airfoil #may have a cantilever support.

The auxiliary airfoil functions to cause a smoothand directed flow of air overand under thestabilizer and elevator in the area of the cutoutportion of the elevator where before, an un-, predicted turbulence of air existed, with the new airfoil, the flow of air moves smoothly over the elevator and cut out space in the elevator with substantially no turbulence in the wake of the elevator. I

It' is to 'be understood thatcertain changes, alterations, modifications and substitutions can be made without departing from the spirit an scope of the appended claims. 1

I claim as my invention:

-l.An aircraft empennage comprising a pair of intersecting stabilizers arranged substantially normal to one another, movable control airfoils secured to said stabilizers, one -of said movablecontrol airfoils having a cut-out portion extending from a point adjacent the intersection of the trailing edges of said stabilizers, to the trailing edge of said control airfoil to permit the movement of the other control airfoil, an auxiliary airfoil mounted on the stabilizer adjacent, and. substantially parallel to, the leading edge of the cut-out movable airfoil, having a lateral extent substantially equal to and spanning the cut-out portion of said airfoil, to effect a smooth flow of air thereover. 2. An aircraft empennage comprising a pair of intersectingstabilizers arranged substantially normal to one another, movable control airfoils secured to said stabilizers, one of said movable control airfoils having a cut-out portion extending from a point adjacent the intersection of the trailing edges of said stabilizers, to the'trailing edge of said control airfoil to permit the movement of the other control airfoil, an auxiliaryairfoil mounted on the stabilizer adjacent and substantially parallel to the leading edge of the As shown in the drawings, particularly Figure 7 6, the length of auxiliary airfoil 8'is slightly cut-out movable airfoil, said auxiliary airfoil having a lateral extent at leas'tequal to and spanning the cut-out portion of said airfoil, to eiiect a smooth flow of'air thereover.

' a ELLISDSHANNON. 

